Comparison of Co- and counter-current modes of operation for wavy minichannel heat sinks (WMHSs)

This study aims to make a comprehensive comparison between the applications of co- and counter-current modes in the wavy minichannel heat sinks (WMHSs). In this regard, the effects of wave-amplitude (wa) and wave-length (wl) are studied at different levels. Water is used as coolant over the Reynolds number (Re) range of 100-900. Nusselt number ratio, friction factor ratio, performance index, max. base temperature difference, and pumping power are reported as quantitative results. An experimental study is also carried out to establish required data for the validation. The outputs illustrate that for both the current modes, the dependence of thermal and hydraulic characteristics on Re increases with increasing wa and decreasing wl, while the counter-current mode is more impressed by the increase of Re compared to the co-current mode. In summary, the Nusselt number ratio ranges from 1.22 to 2.96 for the co-current mode and from 1.23 to 3.17 for the counter-current mode, and the friction factor ratio ranges from 1.09 to 2.73 for the co-current mode and from 1.10 to 2.92 for the counter-current mode, and the range of performance index is from 1.18 to 2.12 for the co-current mode and from 1.19 to 2.22 for the counter-current mode. Eventually, it is found that at the same pumping powers, replacing the co-current mode with the counter-current mode can significantly boost the temperature uniformity in WMHS. The max. base temperature of about 0.84 K is recorded for WMHS with wl = 5 mm at Re = 900. It is worthy to note that the superiority of the counter-current mode increases with increasing wa and decreasing wl.